In Guatemala, and other Latin American countries, it's called "aguinaldo" -- the term used for the bonus government and private sector workers receive this time of the year, their right by law.

The aguinaldo is equivalent to one month's salary. In other words, workers who are eligible for this benefit get twice as much money in December as they do during each of the other 11 months of the year.

The problem is that criminal extortion gangs know this and are increasingly demanding their share of this Christmas bonus. Frequent victims include city bus drivers who also get their aguinaldo. For them, extortion gangs become the Grinch who steals Christmas, and the choice they give bus drivers is harsh: either pay up or we will kill you.

Jorge Garcia, a representative for the City Bus Owners Association in Guatemala City, said the extortion attempts even go beyond Christmas.

"The gangs demand a Christmas bonus. They also demand a summer bonus. Around Easter, they also want a bonus for leisure travel," Garcia told CNN.

According to the Bus Owners Association, so far this year 87 bus drivers have been murdered by criminal gangs, who extort drivers in exchange for safe passage on specific routes. Drivers who refuse to pay face deadly consequences.

Authorities say riders who take buses to go shopping are also likely to be robbed. Victims include workers who also receive their Christmas bonus. The criminals know this and board the buses with the intention of robbing them or stealing Christmas gifts they have just bought for their families.

Edgar Guerra, president of the Guatemala City and Regional Bus Riders Association, said the trend is alarming.

"So far this year, when you count robberies and direct attacks, there have been 44 riders of mass transit murdered and 78 injured in these kind of violent incidents," Guerra said.

Violence in Guatemala is nothing new. The Central American nation lived endured a civil war between 1960 and 1996 that left as many as 200,000 people killed or missing, according to some estimates.

More recently, members of criminal gangs who were deported from the United States and criminals associated with Mexican drug cartels have terrorized the country.

In an international travel alert published last month, the U.S. Department of State said that in Guatemala "violent crime is a serious concern due to endemic poverty, an abundance of weapons, a legacy of societal violence, and weak law enforcement and judicial systems."

This wave of crime affects many other people who are not necessarily directly victimized by the criminal gangs. Every time a bus driver is killed, Guerra says, up to a quarter of a million riders are affected due to cancellations in service.

Guatemalan authorities say they're taking these developments seriously, arresting many of the gangs behind the extortion schemes. Elías Pumay, an investigator with the Guatemalan Interior Ministry who specializes in solving extortion cases, says so far this year they have put 24 criminal gangs out of business with the arrest of 250 suspects.

In his investigations, Pumay has noticed a puzzling new trend: "Interestingly enough, in this type of crime 80% of the perpetrators are women. It's a phenomenon that we're paying close attention to."

Pumay believes those women are following orders from, and acting as messengers for, male gang leaders who have already been arrested and are extorting people from behind bars -- transforming a season of joy into a time of sorrow for their victims.